Blank inverting apparatus for printing presses



1955 E. L. ENGEBRETSON ET AL 2,723,119

BLANK INVERTING APPARATUS FOR PRINTING PRESSES Filed Sept. 25, 1950 3Sheets-Sheet l meg W 31i INVENTORS E url L- Enqebregon Rlckov-d A. HqHeLRokerl d. HaHeq ATTORNEY Nov. 8, 1955 E. L. ENGEBRETSON ET AL BLANKINVERTING APPARATUS FOR PPPPPPPPPPPPP ES Filed Sept. 25, 1950 illllllmmmmmlllllnfl IHEQ I26 @A ZLW, I

ATTORNEY Nov. 8, 1955 Filed Sept. 25, 1950 E. L- ENGEBRETSO BLANKINVERTING APPA ATUS FOR PRINTING PRESSES ETAL 3 SheetsSheet 3 INVENTOIGEur! Enqebreison, k-J-mrd A- HuHeq Robevl" \J. Haueq ATTORNEY UnitedStates Patent BLANK INVERTING APPARATUS FOR PRINTING PRESSES Earl L.Engebretson, Richard A. Halley, and Robert J. Halley, Chicago, Ill.

Application September 25, 1950, Serial No.186,'624 12 Claims. (Cl.271-45)- (Granted under Title, 35, U. S. Code (1952), see. 266) Theinvention described herein, if patented, may be manufactured and used byor for the Government'for governmental purposes, without the payment tous of any royalty thereon.

The present invention relates, to printing machines, and, moreparticularly, to a machine for printing in a single operation upon bothsides of sheet material or for doing m'u'lti-color work upon one sidethereof, and to "mechanism for adapting conventional machines, such asduplicating machines, for performing these operations.

Conventional duplicating machines commonly are of the single coupleoffset lithographic or of the single couple direct printing type. Due tothe demands of the printing processes carried out in these machines,they are capable in a single operation of printing on one side of asheet only. In the past, therefore, when sheets were to be printed onboth sides, it commonly was necessary to print first one side of a sheetand then the other in separate operations. This required the use of twomachines or at least changing of the plate cylinder if a single machinewas used for this purpose. In either event, there was a duplication ofelfort on the part of the operator in twice loading the machine, twicerunning the material through it, and in twice unloading the machine. Atleast twice as much of an operators time was therefore occupied inprinting. upon both sides of a sheet rather than one, or indoingmulti-color work upon one side of the sheet material rather thanmonochrome work. In addition, serious problems arose in securing properregistration of the printed material when more than one impression wasmade on a blank in separate operations. The present invention. isconcerned with mechanism for overcoming these disadvantages of theduplicating machines presently 1n use.

Accordingly, an object of the invention is to provide a new and improvedprinting machine for printing; in a single operation upon the oppositesides of sheet material or upon one side in a plurality of colors.

Another object of the invention is to provide a new. and improved meansfor automatically and mechanically tinverting flexible material in sheetor blank form.

.A further object of the invention is to provide a new and improvedattachment for duplicating machines or like printing machines to adaptthese machines for use in. printing on both sides of a sheet or on oneside in a plurality of colors in a single operation, and which mayreadily be adapted to perform either type of operation;

A more specific object of the invention is to provides. new and improvedmeans for inverting fiexible sheet material including a sheettransportingmeans. which reverses thesdire'ction of translatory movementof a sheet incident to inverting the same and means operating/inconjunction with the sheet inverting means for restoring translatorymovement to the sheet in the direction it moved its inversion.

A more general object of'the inventionis to provide a new and; improved.device asssetgforth .in the foregoing priorto 2,723,119 Ce Patented Nov.8, 1955 2 objects which is simple and sturdy in 'constme-tion "andtherefore inexpensive to manufacture and install, easy to adjust, andfree from liability of frequent breakdown or rapid wear.

These and other objects, advantages and capabilities of the inventionwill become apparent fromv the following description wherein referenceis hadto the accompanying drawings, in which:

Fig. 1 is a diagrammatic view in side elevation of "a pair of printingcouples arranged in tandem for printing upon both sides of sheetmaterial or doing multi-co'l'or work on one side and also showing theimproved inverting mechanism of the present invention;

Fig. 2 is a view similarto Fig. 1; but'takenon the opposite side of themachine from that on which Fig. l was taken showing the printing couplesarranged for doing multi-color work on one side of a blank;

Fig. 3 is a vertical sectional view on an enlarged scale of the improvedinvertingjmechanism of the present invention;

Fig. 4 is a top plan view of'the improved'inverting mechanism of thepresent invention; and

Fig. 5 is a fragmentarydiagrammatic top plan view of a portion of thereversing mechanism of the present in.- vention.

in order fully to disclose the construction and operation of the presentinvention 'andits relationship with a printing mechanism both in anoperational and constructional sense, a pair of printing units orcouples, indicated as a whole by'thenumbers ltland 12, isdiagrammatically shown in Fig. 1, arranged in tandem, with the improvedinverting mechanismv indicated in its. entirety by. the .number 14arranged in operative relationship with these printing couples. In thetworprinting couples. I0 and 12 the operating cylinders are arranged foroffset. lithographic printing as carried out in a common form ofduplicating machine of the type with. which the present invention isparticularly adaptable for use.

Each of the couples shown inFig. 1 includes a plate cylinder 16, a.blanket cylinder 18 andan impression cylinder 20, all rotatablysupported by av stationary frame shown in outline at 22 in. Fig. 1.Associated with the plate cylinders '16 is a dampening-mechanism '24and. an inking mechanism '26. of suitable construction carried upon theframe '22.

Blanks of sheet material such as paper are fed by conventional blankseparating and feeding means. (.notshown.) to. a conveyor or feedboard28 which delivers the blanks to the receiving end of the first couple.The blankseparating. and feeding meansis provided with conventionalmechanism for feeding. blanks to .the feedboard28 and conventionallyoperated stop fingers 130. are provided to release blanks to theoperating cylinders. 'These two means. cooperate. to. feed blanks. tothe operating cylinders in timedrelation to the cycle of the'firstprinting couple 10. Blanks printed upon one side (the outwardly facingside). are stripped from. the impression cylinder 20 by a plurality ofstrippers 32 supported upon. a. bar extending transversely of the couple10.v A plurality of ejector rollers, one-of whichis shown; at 34,cooperate with an ejector roll 36. to deliver printed. blanks. from :thefirst couple to the receiving end of the improved. blankinvertingmechanism 14.

The various operating mechanisms. above, described, comprising the firstprinting couple '10,, are driven by a motor '38 (Fig. 2) housed in abase 40 upon which the couple '10 is mounted; This motor is operativelyconnected to a main-drive shaft 42 (Fig. 2) through abelt M reeved overa pulley on the motor shaftand a pulley 48 on the drive shaft 42-. Asecond 'pulley' 50' on the latter" shaft has abelt 52 reeved thereoverbymeans of which the tapes onthe conveyor or feedboard Zli are 3 driven,while a third pulley 54 on the drive shaft 42 drives a shaft 56 througha belt 58 and a pulley 60 on the shaft 56.

The drive means thus far described is set forth by way of example onlyand may include a pinion 57 (Fig. l) on the shaft 56 meshing with a ringgear 59 on the impression cylinder for driving the latter. In order toeffect positive delivery of printed blanks from the first couple 10 apinion 62 is provided which is driven from the ring gear 59 and drivesejector roll 36 through a suitable pinion 64 on the ejector roll shaftwith which the gear 62 meshes. The plate and blanket cylinders 16 and18, respectively, may be directly driven by suitable gearing from theimpression cylinder 20, and other gearing (not shown) may be provided todrive the inking and dampening mechanisms. The mechanism thus fardescribed may be more or less conventional in construction and operationand is disclosed for the purpose of orienting the present invention anddisclosing its utility.

Referring to Figs. 3 and 4 it will be seen that the inverting mechanism14 comprises essentially an endless conveyor including spaced rollers 66and 68 over which a plurality of conveyor tapes 70 are reeved. Rollers66 and 68 are rotatably supported in a fixed framework in cludingopposed upwardly inclined lateral frame members 72 of generallyrectangular cross-section fixed at their lower ends by welding or thelike to angle brackets 74. The lower end of the inverter frame isslotted along the longitudinal axis of the lateral frame member 72 sothat this inverter frame may be anchored to the frame 22 of couple 10 bymeans of shouldered locking screws 76 (Fig. 4). These screws arethreaded into the frame 22 of couple 10, and the slotted ends of theinverter frame may be engaged upon the same properly to locate theinverter on frame. The locking screws 76 may be provided with hand knobsat some readily accessible place to facilitate tightening or looseningof the locking screws so that the inverter may readily be removed orreplaced. The inverter frame also includes a reinforcing cross-bar orspacer 78 to which the frame members 72 are fixedly secured rigidly tomaintain the inverter frame in assembled relation.

The lower roller 66 is rotatably suported upon a fixed axis adjacent thelower end of the inverter framework, while the upper roller 68 isrotatably journaled upon pins 79 carried in bearing plates 80 adjustablysecured to the upper ends of lateral frame members 72 so that the tapes70 may be tensioned or slackened by adjusting the hearing plates 80longitudinally of the lateral frame members 72. This adjustment may besecured by providing the bearing plates 80 with an elongated slot 82(Fig. 3) through which pass a pair of anchor screws 84, these latterscrews being threaded into the lateral frame members 72. Suitable meansare provided on the lower roller 66 to guide the tapes 70, such as snaprings 86 which resiliently grip the periphery of roller 66 so that theymay be adjusted longitudinally thereof.

The lower roller 66 is rotated to drive the tapes 70 by means of apinion 88 (Figs. 3 and 4) rotatably carried by an arm 90 adjustablerelative to an angle bracket 92 welded or otherwise suitably fixed tothe top side of the right hand lateral frame member 72 (Fig. 4). Arm 90is fixed to this bracket by means of a pair of screws 94 passing througha slot 96 in the arm and threaded into the angle bracket 92 so thatadjustment of the arm and pinion 88 may be obtained in an obviousmanner. Pinion 88 is driven by the gear 64 previously mentioned anddrives the lower roller 66 through a pinion 98 (Fig. 4) fixed relativeto the latter and in mesh with the pinion 88.

As indicated in Fig. 1, the ejector mechanism comprising rollers 34 androll 36 positively delivers blanks from the delivery end of the firstcouple 10 to the upper reach of the conveyor tapes 70 in the invertingmechanism 14. A guard 100 is provided on the forward end of theinverting mechanism, this guard comprising a grill which extends aroundthe upper end of the upper roller 68 to the underside thereof (Fig. 3).Guard is supported from the outer end of the lateral frame members 72 bymeans of plates 102 (Fig. 4) welded or otherwise suitably anchored tothe top side of the lateral frame members 72, and supporting blocks 104removably secured to the plates 102 by means of screws 106. The lateraledges of the guard 100 are received in slots in the sides of the anchorblocks 104 and are held therein by tightening thumb screws 108 againstthese edges. A sheet-metal plate or tray 110 is provided on theunderside of the inverting mechanism 14 and is supported from thelateral frame members 72 by screws threaded into the underside of thelateral frame members. One of these screws is shown at 111 in Fig. 3 andas there indicated springs 112 on the screws bias the forward end oftray 110 away from the lateral frame members. This mounting of the traypermits adjustment thereof toward and from the lower reach of the feedtapes 70.

In order to constrain a blank on the upper reach of the feed tapes 70for movement around roller 68 to the lower reach of the tapes, there isprovided, in addition to the guard 100, two pairs of disc shaped rollers113 and 114 pivotally mounted respectively upon shafts 115 and 116between collars 117 fixed on these shafts. The shafts 115 and 116 aresuitably mounted adjacent their opposite ends in arms 118, rockablycarried at one end of a pair of links 120 which have their opposite endsrockably fixed to mounting blocks 122 rigidly fixed to the underside ofthe guard 100 adjacent its lateral edges. A pair of tension springs 124fixed at opposite ends respectively to the arms 113 and the mountingblocks 104 bias the articulate linkage above described upon which theshafts 115 and 116 are mounted in a direction to hold the guide discs113 and 114 in firm engagement with the periphery of roller 68 on theupper and underside thereof as shown in Fig. 3. Thus, a blank on theupper reach of feed tapes 70 carried forward thereby is guided by theguard 10% and guide discs 113 and 114 around the forward end of theroller 68 to the underside thereof and the lower or return reach of feedtapes 70. Preferably the roller 63 has a friction surface so aspositively to move blanks held in contact therewith by guide discs 113and 114.

It will be apparent that a blank traveling along the lower reach of thetapes 70 will be inverted, i. e., the

printed side will be facing downwardly, and it will be traveling in adirection opposite to the direction in which it was fed to the firstcouple 10.

Movement of blanks in this direction is assisted by an auxiliary ordirectional feedboard indicated in its entirety by the number 126.Auxiliary feedboard 126 comprises a pair of rollers 128 rotatable uponaxes carried in a frame comprising spaced members 130 (Figs. 3 and 5).This frame is supported at one end only upon a transverse shaft 132supported at opposite ends in opposed anchor blocks 134. These blocks134 are adjustably fixed upon supporting rods 136. At one end these rodsare supported by opposite plates or brackets 138 fixed adjacent thedelivery end of the first couple 10, while at their opposite ends theyare supported by posts or bars 140 (Fig. 1) extending upwardly from thebase of the second couple 12 adjacent its receiving end. By reason ofthis mounting of the auxiliary feedboard it may be rocked between theoperative position shown in Figs. 1 and 3 and the inoperative positionshownin Figs. 2 and 5 for a purpose to be described.

The auxiliary feedboard 126 is provided with a plurality of tapes 142spaced from each other a distance corresponding substantially to thespacing of the tapes or certain of the tapes in a connecting conveyor orfeedboard 144 similar to the feedboard 23 and extending from thedelivery end of the first printing couple 10 to the receiving end of thesecond couple 12. Connecting feedboard 144 is suitably supported atopposite ends upon the opposite brackets 138 and the uprights 140 fromwhich the auxiliary feedboard 126 is supported. Since the auxiliaryfeedboard 1 26. is supported only at its forward end, the rear endthereof will rest upon the tapes of the connecting conveyor 144 when theauxiliary board is in the operative position shown in Figs. 1 and 3.Suflicient frictional restraint will be generated between the two setsof tapes to cause the tapes on the auxiliary feedboard 126 to beoperated when the tapes on the connecting conveyor board 144 areoperating. Since the upper reach of the tapes on the connecting conveyorboard 144 travel from right to left in Fig. l, the tapes on the upperreach of the auxiliary feedboard 126 will be caused to travel rearwardlyor from left to right in Fig. 1.

Preferably, shaft 132 supports the rear end of auxiliary feedboard 126elevated slightly above the connecting conveyor 144 so that the roller128 at the rear of this auxiliary board will be maintained elevatedslightly above the tapes on the connecting conveyor 144, and thus blanksmay pass under this roller undisturbed when the auxiliary feedboard istilted to the inoperative position shown in Fig. 2.

Since the direction of translatory movement of the blanks is reversedwhile they are being inverted, it is necessary to provide mechanism forrestoring to the blanks the direction of translatory movement which theyhad prior 'to inversion. Referring to Fig. 1, it will be seen thatinverted blanks are delivered by the combined action of the invertingand auxiliary feed tapes to a tray 146 below the impression cylinder 20in the first couple 10. A plurality of stops 148 upstanding from thistray arrest rearward movement of the inverted blanks. Resilient holddownblank retaining strips 149 are provided to assist in movement of blanksinto and out of tray 146.

At intervals synchronized with the cycle of operation of the secondcouple 12 a shaft 150 rockably mounted in the base of the first coupleis rocked counterclockwise with a substantially snap action. This causesa plurality of elongated fingers or kickers 152 fixed thereon andextending through slots 154 in the tray 146 to snap the rear edge of anarrested blank and project the blank forwardly (to the left in Fig. l)with sufficient force to bring the forward edge thereof into engagementwith the bite between the tapes on connecting and auxiliary feedboards144 and 126 respectively.

Shaft 150 is rocked by linkage which may include a bell crank 156rockable at its intermediate axis upon a fixed shaft 158' and connectedat one of its ends to the rockable shaft 150 by means of pivotallyinter-connected links 160 and 16 2. Link 162 is fixed on shaft 150, andthis shaft is biased in a direction to hold the kickers 152 ininoperative position by a tension spring 163 hooked to an extended endof the pin interconnecting links 160 and 162 and to a clip 165 securedto a suitable fixed part of the frame of the couple 10 as indicatedfragmentarily in Fig. 1. Bell crank 156 is rocked by a cam 164 on acamshaft rota-tably driven from the impression cylinder ring gear 5.9 bygearing including a pinion 166 on the camshaft (Fig. 1) and a compoundgear 167. The mechanism for rocking shaft 159 obviously is arranged tooperate the kickers 152 immediately following each deposit of aninverted blank in the tray 146.

In order that the printed matter appearing on opposite sides of a blankshall register properly the second couple 12 is driven from the firstcouple 10 in synchronism with the latter by means of a sprocket chain168 (Fig. 2) or the like. This chain is engaged over a sprocket 170 onthe shaft 56 (Fig. 2) in the first couple 1!) and asprocket 172 on theshaft in the second couple 12 corresponding to shaft 56 in the firstcouple so that the two couples operate together and at uniform speed.Preferably a suitable clutch indicated diagrammatically at 174 in Fig. 2is provided between sprocket 17.0 and shaft 56 to provide for theadjustment necessary initially to bring the two couples into timedrelation or thereafter to bring them into timed relation when the deviceis changed from two sided to one sided work or vice versa. 7

It will be noted in Fig. 2 that the second eouplelz' is provided with ashaft 176 corresponding to shaft 42 in the first couple 10. This shaft176 is driven from the shaft upon which sprocket 172 is mounted throughgearing (not shown) and has a pulley 178 thereon through which the tapeson connecting conveyor board 144 are driven by means of a belt 180.

Briefly, to describe the operation of the present invention referencewill first be had to Fig. 1 which shows the mechanism arranged to printblanks on their opposite sides. Blanks such as sheets of paper are fedby conveyor 28 to the bite of the first couple 10 in timedrelation tothe operation of the blanket and impression cylinders 18 and 20respectively therein so that printed matter registers properly on theoutwardly facing side of the blanks passing through this first couple.

As the impression cylinder 20 advances, blanks are stripped therefrom bythe strippers 32 and guided by the latter between the ejector rollers 34and roll 36 which cooperate to deliver the blanks printed side up to theupper reach of the tapes 70 in the inverting mechanism 14. These tapesare driven in the manner previously described in a direction to causethe upper reach thereof to move away from the first couple 10 so that ablank thereon is carried beneath the guard and between the upper roller68 and the upper and lower guide roller discs 1'13 and 114 respectivelywhich, along with the guard 100,, constrain the blank for movement tothe underside of the inverting mechanism onto, auxiliary feedboard 126whereupon this feedboard directs the blank toward tray 146 where itsmovement is arrested by stops 148.

It will be apparent that blanks are delivered to the tray 146 inverted,i. e., with their printed sides facing downwardly. Following arrest ofmovement of a blank in the tray 146 the kickers 152 are rockedcounterclockwise by the mechanism previously described and project theinverted blank forward into the bite between connecting conveyor board144 and auxiliary feedboard 126. Thereupon, the inverted blank is fed bythe connecting conveyor board 144 to the receiving end of the secondcouple 12.

In the event it is desired to do multi-color work on one side of blankmaterial, the lock screws 76 are loosened and the inverting mechanism 14removed as a unit from the first couple 10. The auxiliary feedboard 126is then rocked to the position shown in Figs. 2 and 5 clearing its tapesfrom the tapes on connecting conveyor board 144'. It will be apparenttherefore that blanks printed on their upwardly facing side will bedelivered by the ejector roll 36 and rollers 34 to the connectingconveyor board 144 printed side up so that they will be printed onthis'sa'rne side when they pass through the second couple 12. Thus byusing diiferent colored inks in the two couples multi-color work may bedone upon blank material in one operation. Delivery of work from thesecond couple may be elfected by conventional apparatus.

In order to assure passage of the inverted blanks through the secondcouple 12 properly aligned with the printing cylinders of the latter, aside register jogger (not shown) of conventional construction isprovided at the receiving end of the second couple 12. This jogger isoperated from the stacker jogger cam shaft of the second couple so thatit is always in time with the second couple irrespective of the timingbetween the first and second couple's.

From the foregoing description of the construction and operation 'of thepresent invention it should be apparent that a blank invertingmechanismof exceedinglysimple construction has been devised adapting printingunits-arranged in tandem for printing on opposite sides of flex-- ibleblank material. Furthermore, this mechanism is readily removable so thatthe printing units may be used for placing a plurality of impressions onone side of a blank as in doing multicolor work. Either type of printingmay be done as a single operation thus reducing handling by an operatorand reducing the time consumed I by one-half or more.

through the use of substantially the same or equivalent means.

We claim:

l. Mechanism for inverting blanks of flexible sheet material comprisingendless conveyor means having reaches moving in different directions,means to guide blanks advanced by said conveyor from one reach thereofto the other so as substantially to invert said blanks and to reversethe direction of translatory movement thereof, means for receivinginverted blanks and arresting translatory movement thereof, a rockableshaft, means for rocking said shaft with a snap action, and a pluralityof fingers rocked into striking engagement with the edge of an arrestedblank most advanced in the reverse direction of movement in response torocking movement of said shaft for imparting movement to arrested blanksin a direction corresponding substantially to their direction ofmovement prior to inversion.

2. Mechanism for inverting blanks of flexible sheet material comprisingendless conveyor means having reaches moving in different directions,means to guide blanks advanced by said conveyor from one reach thereofto the other so as substantially to invert said blanks and to reversethe direction of translatory movement thereof, means for receivinginverted blanks and arresting reverse translatory movement thereof, aplurality of fingers mounted for rocking movement into strikingengagement with the edge of an arrested blank most advanced in thereverse direction of movement for imparting movement thereto in adirection corresponding substantially to its direction of movement priorto inversion, means to rock said fingers including a bell crank, meansincluding linkage operatively connecting one end of said bell crank andsaid fingers, and a rotatable cam for rocking said bell crank on itsintermediate axis at a predetermined point in the rotation of said cam.

3. Mechanism for inverting flexible sheet m'aterial comprising arotatably driven roller, means for receiving sheet material and fortransporting the same towards said roller, means to guide sheet materialover said roller so as to invert the same and to reverse its directionof translatory movement incident to the inversion thereof, a slottedstationary receiver for inverted sheet material, a shaft extendingtransversely of said receiver and rockably journalled in vertical spacedrelation thereto, a

pluralityof fingers fixed upon said shaft and having a free endprojecting into the slots in said receiving means, means for rockingsaid shaft with a snap action in timed relation to the deposit of asheet in said receiver to cause said fingers to strike the rearwardlyfacing edge of the deposited sheet and impart motion thereto in adirection corresponding substantially to the direction of translatorymovement of said sheet prior to its inversion, and means for receivingthe said sheet material from said receiver and transporting the samefrom said inverter.

4. Mechanism for inverting blanks of flexible sheet 8 material duringthe course of their movement in a predetermined direction comprising, asingle endless conveyor having forward and rear rollers spaced from eachother and one or more endless belts trained over said rollers to providea first reach for receiving and conveying blanks toward the forwardroller and a second reach traveling in the opposite direction, means toguide blanks on the first reach around the forward side of said forwardroller to said second reach so as to invert said blanks and reverse thedirection of translatory movement thereof, means cooperating with saidconveyor to continue movement of inverted blanks in a reverse directionbeyond said rear roller, means to arrest and receive inverted blanks tothe rear of said rear roller, and means to strike the rearwardly facingedge of an arrested blank in timed relation to the arrest of blanks withsufficient force to propel arrested blanks out of said arresting means.

5. In a mechanism for inverting blanks of flexible sheet material thecombination comprising, an endless conveyor including a frame, a forwardand a rear roller rotatably journaled respectively in opposite ends ofsaid frame and one or more endless tapes drivingly trained over saidrollers, means for rotatably driving one of said rollers, a guardincluding a flat part extending forwardly from a region forward of therear roller to define an inlet for receiving blanks to be inverted andan arcuate part concentric with the forward side of said forward rollerand terminating in an outlet for inverted blanks on the side of saidconveyor opposite said inlet, at least two series of idler rollers,rigid members to support the axis of said series of idler rollersadjacent opposite ends thereof so as to maintain said series in parallelspaced relation, links pivotally connected to an intermediate part ofsaid rigid members and to a fixed axis in said inverting mechanism andmeans yieldably to urge said links and rigid members in a direction tomaintain said idler rollers in frictional engagement with the forwardside of said forward rollers at circumferentially and axially spacedpoints.

6. In a mechanism for inverting blanks of flexible sheet material thecombination comprising, an endless conveyor including a frame, a forwardand a rear roller rotatably journaled respectively in opposite ends ofsaid frame and one or more endless tapes drivingly trained over saidrollers, means for rotatably driving one of said rollers, a guardincluding a flat part extending forwardly from a region forward of therear roller to define an inlet for receiving blanks to be inverted andan arcuate part concentric with the forward side of said forward rollerand terminating in an outlet for inverted blanks on the side of saidconveyor opposite said inlet, and means to cooperate with the guard inguiding blanks from the inlet around the forward side of said forwardroller to said outlet so as to invert blanks carried by said tapesincluding a plurality of idler rollers, articulate linkage to mount saididler rollers for free rotation on axes parallel to the axis of saidforward roller and rockable around an axis which is movable in adirection to vary the radial spacing thereof from the axis of saidforward roller, and means for biasing said linkage to bring said rollersinto frictional engagement with the forward side of said forward rollerat circumferentially and axially spaced points.

7. In a device for printing upon the opposite sides of blanks of sheetmateral the combination comprising, spaced similar first and secondprinting couples, an endless connecting conveyor for transporting blanksbetween the delivery end of said first couple and the receiving end ofthe second couple, an endless conveyor type inverter to receive blanksfrom said first couple, invert the same and reverse the direction oftranslatory movement thereof, said inverter having a lower reach spacedupwardly of the connecting conveyor, a third endless conveyor betweensaid connecting and inverting conveyors including an upper reach drivenin the same direction as the lower reach of the inverting conveyor so asto assist the latter in moving inverted blanks reversely and a lowerreach traveling in the same direction as the upper reach of theconnecting conveyor, means to arrest translatory movement of invertedblanks including means to station arrested blanks opposite the bite ofsaid connecting and third conveyor, means for driving said couples,connecting conveyor, inverting and third conveyors in timed relation,and means driven in timed relation to the sequence of said couplespositively to propel arrested blanks into the bite of said third andconnecting conveyors individually and in a predetermined sequence.

8. A printing device as claimed in claim 7 wherein said drive meansincludes a single source of power operatively connected to drive one ofsaid couples and means is provided operatively to connect said twocouples for simultaneous operation when said one couple is drivenincluding means to vary the timing between the two couples.

9. In a device for printing upon the opposite sides of blanks of sheetmaterial the combination comprising, spaced similar first and secondprinting couples, an endless connecting conveyor to receive blanksdischarged by said first couple and transport the same to the secondcouple, a unitary blank inverter, means detachably to mount saidinverter at a position to intercept blanks discharged by the firstcouple, said inverter reversing the direction of movement of the blanksincident to inversion thereof, an auxiliary endless conveyor mounted toassume a position intermediate the connecting conveyor and the inverterwhen the latter is in position in frictional driving engagement with theconnecting conveyor and to be swung when the inverter is dismounted toclear the connecting conveyor for directly receiving the blanksdischarged by the first couple, means to arrest translatory movement ofinverted blanks including means to station arrested blanks opposite thebite of said connecting and auxiliary conveyors, means for driving saidcouples, conncting conveyor and inverter in timed relation, and meansdriven in timed relation to the sequence of said couples to propelarrested blanks into the bite said auxiliary and connecting conveyorsindividually in a predetermined sequence.

10. Mechanism for inverting blanks of flexible sheet material comprisingendless conveyor means having reaches moving in difierent directions,means to guide blanks advanced by said conveyor from one reach thereofto the other so as substantially to invert said blanks and to reversethe direction of translatory movement thereof, means for receivinginverted blanks and arresting translatory movement thereof, a rockableshaft, means for rocking said shaft with a snap action, a plurality offingers rocked into striking engagement with the edge of an arrestedblank most advanced in the reverse direction of movement in response torocking movement of said shaft for imparting movement to arrested blanksin a direction corresponding substantially to their direction ofmovement prior to inversion and resilient means for guiding the rearedge of inverted sheets into said inverted blank receiving means andlightly to hold the same in position to be struck by said fingers.

11. Mechanism for inverting blanks of flexible sheet material during thecourse of their movement in a predetermined direction comprising, asingle endless conveyor having forward and rear rollers spaced from eachother and one or more endless belts trained over said rollers to providea first reach for receiving and conveying blanks toward the forwardroller and a second reach traveling in the opposite direction, means toguide blanks on the first reach around the forward side of said forwardroller to said second reach so as to invert said blanks and reverse thedirection of translatory movement thereof, an auxiliary endless conveyorcooperating with said inverting conveyor to continue movement ofinverted blanks in a reverse direction beyond said rear roller, means toarrest and receive inverted blanks to the rear of said rear roller, andmeans to strike .the rearwardly facing edge of an arrested blank intimed relation to the arrest of said blanks with sufiicient force topropel arrested blanks out of said arresting means.

12. In a device for printing upon the opposite sides of blanks of sheetmaterial the combination comprising, spaced similar first and secondprinting couples, an endless connecting conveyor for transporting blanksbetween the delivery end of said first couple and the receiving end ofthe second couple, an endless conveyor type inverter to receive blanksfrom said first couple, invert the same and reverse the direction oftranslatory movement thereof, said inverter having a lower reach spacedupwardly of the connecting conveyor, a third endless conveyor betweensaid connecting and inverting conveyors in frictional driving engagementwith said connecting conveyor including an upper reach driven in thesame direction as the lower reach of the inverting conveyor so as toassist the latter in moving inverted blanks reversely and a lower reachtraveling in the same direction as the upper reach of the connectingconveyor, means to arrest translatory movement of inverted blanksincluding means to station arrested blanks opposite the bite of saidconnecting and third conveyor, means for driving said couples,connecting conveyor, inverting and third conveyors in timed relation,and means driven in timed relation to the sequence of said couplespositively to propel arrested blanks into the bite of said third andconnecting conveyors individually and in a predetermined sequence.

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